1. Field of the Invention
This invention relates to air conditioners and in particular to means for controlling the operation of air conditioners, such as central air conditioners, having outdoor condenser and compressor units and indoor evaporator and thermostatic control units.
2. Description of the Prior Art
Central air conditioners conventionally employ outdoor condenser and refrigerant compressor units which are connected to indoor evaporator units and controls by suitable ducts and wiring for providing relatively high capacity indoor air conditioning. Such systems utilize thermostatic controls which conventionally incorporate manually adjustable means for selecting a desired indoor temperature and automatically controlling the operation of the system to obtain such temperature.
At times, such air conditioning systems may become inoperative for any one of a number of different reasons. Illustratively, the system may be shut down because of a high thermostat setting. Alternatively, the apparatus "Heat-Off-Cool" on-off switch may not be in the "Cool" position. Further, power to the system may be disrupted or the voltage of the power supply may drop to a low level insufficient to permit operation of the system. The power interruption may be momentary or continuous.
Additional malfunctioning problems may arise from clogged air filters, furnace blower or evaporator coils. Malfunctioning of the furnace blower, such as from a blown fuse or a broken drive belt, may also cause a failure of the system. Additionally, where adjustable registers are utilized in the air distribution system, restricted, obstructed, or closed registers may similarly cause a failure of the system.
Additional failures may occur because of failure of the power supply to the outdoor condensing unit. Alternatively, such systems are caused to be inoperative when the outdoor temperature is below a preselected temperature, such as 60.degree. F. A restriction or obstruction of the outdoor condensing unit coil may further cause malfunctioning of the system.
Such malfunctionings heretofore have ordinarily required a check of the system by a service technician inasmuch as the prior systems did not provide for indicating to the user specific information as to the cause of the failure, permitting the user, in certain instances, at least, to remedy the malfunction. The requirement of a service technician, in many cases, has been unnecessary, time-consuming, and costly. It is obviously desirable to permit the user of the apparatus to effect simple restarting of the apparatus where the malfunction is of a simple nature so as to avoid the need for the services of a service technician. It is further desirable to provide to the user some indication as to the nature of the malfunction so that suitable servicing of the apparatus, of which the normal user is capable, can be effected without the need for the services of a service technician. Alternatively, where the malfunction is of the type that should be handled by a service technician, it is desirable to provide an indication of this fact to the user so as to avoid undesirable attempts by the user to restart the system without such service technician services. Further, the indication of the malfunction facilitates repair of the air conditioner by the service technician.
Because of the present energy crisis, the problem of low voltage conditions is becoming more prevalent. Such power supply conditions may cause permanent damage to the system. However, it has been found that, quite often, the low voltage condition is temporary and, thus, it is desirable to provide some means for preventing the air conditioner from starting under low voltage conditions and automatically resetting the system upon restoration of the preselected minimum voltage. Additionally, where the stoppage of the system is caused by a power interruption, it is desirable that the system be automatically restarted upon restoration of the power.
In the case of the other above discussed malfunctionings, the user must make some correction to the system prior to the restarting of the system and, thus, a manual reset of the system is desirable. Thus, before restarting the system where the malfunctioning has occurred because of clogged filters, evaporator coils, outdoor condensing unit coils, blown fuses, etc., these conditions must be corrected before an attempt to restart the system should be made.
A number of prior art patents disclose different controls for use with air conditioning apparatus.
Alden J. Ritter et al, in U.S. Pat. No. 2,884,767, disclose a control apparatus having a resettable safety circuit reset upon de-energization of the fan circuit. The control provides an automatic reset upon power failure and requires the operation of a reset button to restart the system after other system failures. More specifically, the control is reset by adjustment of a fan switch.
In U.S. Pat. No. 3,064,444 of William K. Kyle, a safety control circuit for motors or refrigerant compressors is shown having means for permitting manual reset of the circuit in the event of an interruption due to an overload condition and an automatic reset in the event of refrigerant pressure cutout.
Lawrence H. Foster et al, in U.S. Pat. No. 3,100,383, disclose a control for refrigerators having alarm means with indicator lamps carried on a control console mounted on the top of a refrigerator for indicating different abnormal conditions of the refrigerator.
Norman P. Bergeron, in U.S. Pat. No. 3,594,749, discloses a monitoring system for refrigerated display cases provided with remote monitor lights for indicating the status of each of several display cases. A jumper means is provided for actuating a flasher to identify malfunction of critical components of the apparatus.
In U.S. Pat. No. 3,628,346, Cecil G. Lagrone, Jr. discloses an apparatus for indicating thermal and air velocity conditions of air in the plenum of a central air conditioning system such as upon a malfunction or failure of the fan or motor compressor of the system.
A monitoring system is shown in U.S. Pat. No. 3,731,294 of Leslie Vass which includes a plurality of sensors, a plurality of indicators, and a controller responding to the sensing of a predetermined condition to cause a master control to perform a preselected control function.
U.S. Pat. No. 3,742,303 of Ernest C. Dageford, shows a compressor protector system monitoring the internal temperature of a compressor motor. The system automatically rechecks after a predetermined period of time to determine whether the fault causing the stopping of the compressor has been cleared. The control automatically starts the compressor if the fault has been so cleared.